#include <stdio.h>
#include <stdlib.h>

int main()
{
    int a11,a12,a13,a21,a22,a23,a31,a32,a33;
    while(scanf("%d %d %d %d %d %d %d %d %d",&a11,&a12,&a13,&a21,&a22,&a23,&a31,&a32,&a33)== 9)
    {
        int sum;
        sum = a11*a22*a33+a12*a23*a31+a13*a21*a32-a11*a23*a32-a12*a21*a33-a13*a22*a31;
        if(sum < 0)sum = -1*sum;
        printf("%d.00\n",sum);
    }
}
